- 8 - 
After-ripening period of resting sporangia varies with 
conditions. Under favorable conditions most ripen and germin- 
ate within a year, a few persisted to 3^- years. Little 
moisture required for germination. Rain causes more in- 
fection than capillary moisture. Limits of spnere of in- 
fection are 10 cm. laterally, 10 to 15 cm. upward, 15 to 
20 cm. downwards in a vertical direction. "The zoospores are 
primarily transported toward the tubers by currents of soil 
water, their own movements being of little significance in 
this respect. In the early stages of their journey, the 
motion of the zoospores appears to be without definite di- 
rection: only in the immediate vicinity of the tubers is a 
chemotactic stimulus probably exerted by the susceptible 
parts. " 
(9) Glynne, Mary D. 
1934 Infectivity of summer sporangia of Potato wart disease 
in incipient infections on varieties immune in the field. 
Nature 134: 253, 1934. (Abstr. in R.A.M. 14: 55, Jan. 1935.) 
Wart developed in the laboratory on potato varieties 
apparently immune in field. Infection soon sloughed off. 
"Inoculations on the susceptible Arran Chief variety from 
such incipient infections bearing summer sporangia which 
developed in the laboratory on Snowdrop, Bishop, and Ben 
Cruachan (apparently immune in the field) gave positive re- 
sults." (R.A.M.) 
(10) Hilli, A. 
1932 (The reasons of the spread of potato wart (Synchytrium 
endo b ioticum (Schilb.) Perc.) in Finland and abroad.) Valt. 
Maatabouskoet. Julkais. No. 46. 249 p. 1932. From the 
English abstract p. 231 - 249: 
p. 232. speaking of factors of spread "The most important 
of these are the transportation and trade of potatoes and 
the way of cultivation due to the kind of settlement. Other 
factors of culture (the transportation by soil, manure, 
fertilizers, animals, people and implements and by the work 
of eradication of potato wart) are in this respect of greater 
significance than natural factors (moisture, temperature, 
light, oxygen, kind of soil, soil reaction, host-plants, 
parasites). Writer thinks wart as tolerant as potato. Suf- 
ficient moisture present in cultivated land to germinate 
wart spores any time. Resting sporangia endure long drought, 
p. 233. "On the surface flow of water potato wart can be 
carried at least 200 metres in cultivated lands just being 
tilled, as experiments carried out in Pyhajarvi parish in 
Uusimaa ad. dist. have shown." Wart organism endures cold 
and heat better than host. Light of little significance. 
Nature of soil has no great influence. Influence of soil 
reaction slight. Influence of other hosts slight. 
